In the industrial environment, metal contamination is often thought of as an airborne, respiratory hazard.

However, metals can also represent an ingestion risk.

The Gradient study establishes that metal residue on "clean" laundered shop towels can transfer to hands during use, then to the face and mouth where they can become an ingestion hazard.

Many exposure models have explained the ease of transfer from hand to mouth; this is recognized by multiple federal agencies such as the U.S. Environmental Protection Agency (EPA).

Given that an average person touches their face up to 16 times per hour, this exposure pathway's importance becomes clear.

The problem is, workers cannot see, smell or feel heavy metal contaminants on shop towels, so they may ultimately ingest the toxic metal residue from hand-to-mouth movements without knowing it.

This is a significant issue, as chronic metal exposure, at sufficient doses, could result in various negative health effects including cancer and reproductive problems.

Gradient research compared predicted metal exposure from shop towels against federal and state health-based toxicity limits.

The firm conducted this analysis after 26 U.S. and Canadian companies submitted laundered shop towel samples to an independent lab, which tested them for 29 metals including antimony, beryllium, cadmium, cobalt, copper, iron, lead, molybdenum and nickel, as well as oil and grease.

When comparing metal exposure from laundered shop towels against well-known regulatory benchmarks, the findings were alarming:

Permissible exposure limits from drinking water

Metal exposure from using laundered shop towels may exceed the permissible levels allowed in drinking water as set by the EPA in the Safe Water Drinking Act.

According to Gradient's latest research, workers who use the typical amount of shop towels may be exposed to metals such as lead, chromium, cadmium and antimony at levels exceeding those allowed by the maximum contaminant levels (MCLs) or action levels (AL) for drinking water.

For instance, the daily intake of lead from shop towels may be up to 21 times higher than the intake associated with the lead action level.

When workers must handle shop towels, they have the right to know about the unnecessary and potentially serious health risks they are being exposed to on a daily basis in order to take precautions, such as:

Do not wipe your hands, face or mouth with laundered shop towels; to avoid skin contact, gloves are recommended

Always thoroughly wash your hands with soap and water and dry with a clean paper towel before eating or touching your eyes or mouth

Wash your hands and face before leaving work to avoid the potential of taking heavy metal residues home to your family

Do not take home laundered shop towels or wash them along with your clothes at home.

When laundered shop towels are delivered as clean, they should, in fact, be clean.

Workers today experience an unnecessary exposure to toxic metal residues from regular shop towel use — this is unacceptable.

Metal exposure is cumulative and may have long-term health consequences.

We must protect workers from this potentially dangerous, hidden workplace hazard.

The best way to do that is to throw in the towel on dirty shop towels.

Kim MacDougall is a research scientist at Kimberly-Clark Professional, which aspires to advance exceptional workplaces where people feel safer, healthier and more productive. MacDougall has served the cleaning, hygiene and workplace safety industries for more than 25 years. She has spearheaded efforts to help organizations choose the right disposable wiper for various tasks; for instance, by creating this self-service tool: www.KCProductSelector.com. To learn more about the shop towel safety issue, go to www.TheDirtOnShopTowels.com and follow @KCProf_NA on Twitter.